Should you tip for carpet cleaning?

I purchased one of those daily deal promotions to have my living room carpet cleaned. I saved 50% but then I noticed the Groupon coupon had a note about tipping. Are you supposed to tip for carpet cleaning? I did tip him based on the non-discounted price, but wonder if I really needed to or not.

I believe it is his own business and he also does all of the work, if that makes a difference.